Atom Configuration for JavaScript (JSX) with Fira Code as Font Ligature

styles.less

//Custom configuration

atom-text-editor {
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  font-family: "Operator Mono";
  font-size: 16px;
  font-weight: 500;
  line-height: 1.5;
}

atom-text-editor.editor {
  .syntax--storage.syntax--type.syntax--function.syntax--arrow,
  .syntax--keyword.syntax--operator:not(.accessor):not(.syntax--new),
  .syntax--punctuation.syntax--definition:not(.syntax--tag):not(.syntax--bracket):not(.syntax--brace) {
    font-family: "Fira Code";
  }

  .syntax--string.syntax--quoted,
  .syntax--string.syntax--regexp {
    -webkit-font-feature-settings: "liga" off, "calt" off;
  }

  .entity.other.attribute-name,
  .comment,
  .syntax--entity.syntax--other.syntax--attribute-name.syntax--js,
  .syntax--keyword.syntax--control.syntax--js,
  .syntax--storage.syntax--modifier.syntax--js,
  .syntax--storage.syntax--type.syntax--class.syntax--js,
  .syntax--variable.syntax--language.syntax--js {
    font-style: italic;
  }
}

atom-panel.tool-panel {
  font-size: 0.88em;
}

.entity.other.attribute-name {
  font-style: italic;
}